Recent progress on flexible and stretchable piezoresistive strain sensors: From design to application

Flexible and stretchable piezoresistive strain sensors which can translate mechanical stimuli (strain changes) into electrical signals (resistance changes) provide a simple and feasible detection tool in the field of health/damage monitoring, human motion detection, personal healthcare, human-machine interfaces, and electronic skin. Herein a detailed overview is presented on both strategies for sensing performance improvement and progress to medium or large-scale fabrication. A broad range of matrices/substrates and incorporated nanomaterials is covered and attention is paid to the current state-of-the-art of feasible but low-cost manufacturing methods. The sensor design parameters include sensitivity (gauge factor), stretchability, linearity, hysteresis, biocompatibility, and self-healing potential. Starting from fundamental sensing mechanisms, i.e. the tunneling effect, the disconnection mechanism, and the crack propagation mechanism, examples are provided from lab to application scale.